Fabrication of uranium-aluminum alloys



" atent 2,917,383 Patented Dec. 15, 1959 ice FABRICATION OF URANIUM-AL ALLOYS No Drawing. Application July 29, 1949 Serial N 0. 107,633

1 Claim. (Cl. 75-214) This invention deals with the fabrication of uraniumaluminum alloys, and in particular with uranium-aluminum alloys which have a relatively high uranium content, as they are used, for instance, in the construction of power-producing neutronic reactor plates.

It has been found desirable in the construction of reactor plates for power-producing piles to use uranium in the form of an alloy with aluminum wherein the uranium content is at least 40% by weight. Difficulties, however, wereencountered in the fabrication of structural members of such alloys because all uranium-aluminum alloys with a uranium content of above about 14% were found to contain the compounds UAl and UAl both of these compounds occur in large crystals which cannot be worked, for example, by cold-rolling. Thus, shaping of uranium-aluminum alloys with higher uranium contents has been found impossible heretofore.

It has been tried to produce shaped articles from a uranium-aluminum alloy with a uranium content of 70% by melting a mixture of analogous portions of the metals, cooling the alloy obtained, powdering the alloy, and then shaping the powdered alloy. However, similar difliculties existed in this case as in the previously described instances, namely, the product obtained by this procedure consisted of a mixture of UA1 and UAl and due to the presence of the latter compound, the powder was not workable. Experiments have also been carried out by which the uranium was added in the form of UBe also, the product obtained by this process could not be worked.

It has then been tried to add a powdered uranium-aluminum compound to aluminum in molten form in an argon atmosphere and in the presence of various fluxing agents; however, this process did not lead at all to the result desired, because the uranium-aluminum compound was oxidized before it was wetted by the molten aluminum so that even alloying was impossible.

It is thus an object of this invention to provide a method for preparing a uranium-aluminum alloy with a high uranium content which is free from the disadvantages described above.

It is another object of this invention to provide a method of preparing uranium-aluminum alloys with a high uranium content which yields a final product of a fine grain structure and homogeneous dispersion and which is workable.

It is still another object of this invention to provide a method of preparing uranium-aluminum alloys with a high uranium content in which no loss of materials occurs by oxidation.

These and other objects are accomplished by mixing aluminum powder and a powdered intermetallic uranium compound, compressing the mixture into the shape desired, and then sintering it.

A great number of uranium compounds have been found suitable for the process of the invention; for instance, UAl UAl UA1 and UBe have been used with great satisfaction. These aluminum compounds may be obtained by melting the ingredients in the proper proportions, for instance, in a magnesium oxide crucible; although melting may be carried out in air, an atmosphere of argon has been found preferable.

The temperature for heat-treating the mixture of aluminum and uranium-aluminum powders is preferably within the range of 450 and 600 C.; temperatures close to 600 C. gave the best results. In addition to heattreating, the powder mixture may optionally be subjected to a mechanical treatment which may be carried out simultaneously with the heat-treatment; thus, for instance, the compressed powders may behot-rolled. The aluminum powder and the powder of the uranium-aluminum compound may be mixed in the proportions desired of the final alloy, because loss of metallic ingredients does not occur by oxidation or other destructive reactions.

Example I Example II 74% uraniumand 26% by weight of beryllium were mixed and melted whereby UBe was obtained. This compound, whichshowed a high degree of brittleness, was pulverized and mixed with suflicient aluminum to reduce the total uranium content of the mixture to 20%. This mixture was then sintered at about 600 C., whereby a dense non-brittle compact was obtained. The compact was jacketed in aluminum, and the unit was then satisfactorily rolled at 600 C.

The materials obtained by the two examples were metallographically examined and all of them were found to be free from voids or segregation.

It will be understood that all of the details and the examples were given forillustration purposes only and that the invention may be modified in accordance with the spirit of the invention and the scope of the appended claim. 7

What is claimed is:

The method of producing a workable article of a uranium-aluminum alloy having a uranium content of above 14% by weight, comprising mixing aluminum powder and a powdered uranium intermetallic compound selected from the group consisting of UAl UAl UAl and UBe in an amount sufiicient to have at least 14% but not over of uranium in the mixture, compressing said mixture into the shape desired of said article, and sintering said compressed assembly between 450 and 600 C.

References Cited in the file of this patent UNITED STATES PATENTS 927,935 Von Bolton July 13, 1909 1,648,954 Marden Nov. 15, 1927 1,670,463 Marden May 22, 1928 1,728,942. ,Marden Q Sept. 24, 1929 

